1. Field of the Invention
The present invention relates to a light-receptive module used in optical communication or the like, and more particularly to a light-receptive module comprising a light-receptive element and an optical fiber disposed on a board, and a method for manufacturing the same.
2. Description of Related Art
In conventional light-receptive modules, for example, a light-receptive element is mounted on a submount board and an optical fiber is secured to a silicon board with a guide slot provided, together with an optical fiber retainer. The submount board, silicon board, and pre-amplifier are secured on a package in position.
Positions in a direction perpendicular to an optical axis depend on the mounting position of the light-receptive element in a carrier. Positions in an optical axis direction and those in a direction horizontal to the optical axis are determined by the mounting position of the carrier with respect to the optical axis of the fiber. In this configuration, a mounting precision is at best about .+-.20 .mu.m and therefore it is difficult to obtain a high coupling efficiency with a satisfactory yield for a light-receptive element whose light receive diameter is 50 .mu.m or less.
Since a carrier intervenes, the capacity of the light-receptive element plus the capacity of the carrier is regarded as the input capacity of a pre-amplifier of the following stage. For this reason, this structure is not suitable for high-speed, broadband modules requiring low capacity.
Light-receptive modules of a conventional configuration are susceptible to positional deviation due to this structural combination. This is because a light-receptive element and an optical fiber are mounted on different boards. The positional precision of the light-receptive element and the optical fiber 1 deteriorates due to a total of a positional deviation in the coupling of the light-receptive element 7 and the submount board 23, a positional deviation in the coupling of the optical fiber 1 and the silicon board 4, and a positional deviation between the silicon board and the submount board. A positional precision provided by this configuration is at best about .+-.20 to 30 .mu.m. Therefore, it is difficult to obtain a high coupling efficiency with a satisfactory yield for a light-receptive element whose light receive diameter is 50 .mu.m or less.
Additionally, it is difficult to apply conventional light-receptive modules to high-speed light-receptive modules. Since a light-receptive element is mounted on a submount board, an extra capacity will be added in addition to the capacity thereof. Furthermore, the need for a wiring with an electrode pattern bent 90 degrees on the submount board will inevitably bring about the parasitism of complex wiring capacities, wiring inductance, and the like. Generally, since pre-amplifiers performing high-speed operation are subject to the influence of an input section, this configuration in which extra parasitic components would be added is not suitable for light-receptive modules performing high-speed operation.